Advanced excavation damage zone behaviour prediction for immediate and delayed construction response during deep tunneling and deep geological repository development

处置高放射性核废料是所有核电国家面临的一项重大工程挑战。专家们一致认为，地下处置是唯一可行的长期选择。加拿大同许多国家一道，正在推进高放（乏燃料）废物处理的研究和先进计划，目前正在为其自己的地下贮存库选择场址。对于加拿大人来说，这样一个储存库的最终成本将达到数十亿美元，而长期的生存能力和安全性依赖于储存库基础设施周围的挖掘破坏区（EDZ）的管理。安全评估主要关注的是EDZ的最大范围和受损光晕内流体流动性增加的梯度。***在EDZ内是靠近开挖边界的断裂程度较高的破坏区（HDZ）。EDZ/HDZ的阶段性、时变和动态响应也是深井掘进的关键问题，具有相当高的经济价值。在加拿大和世界各地，用于民用基础设施或矿山通道的隧道正在越来越深的脆性岩体中开发。虽然在采矿中通常会考虑到HDZ的脆性响应，但在最近的许多世界级隧道项目中，HDZ的脆性响应在设计阶段往往被忽视，严重影响了工人的安全，延误了工期，增加了成本。***在核废料储存库中，竖井中可检测到的HDZ通常在使用寿命结束时在回填之前被移除，因此不考虑在竖井安全评估中。然而，在施工期间和施工后，HDZ的性质和时间依赖性响应将影响随后的EDZ行为。在测序、安全性和支持方面，这也将是一个工程挑战。不同的候选地点将有不同的脆性HDZ预测水平和动态破裂程度，必须在施工前识别，以便进行设计调整。***由该发现基金资助的拟议研究建立在以前nserc资助的进展（表征损伤起始的一般性质）的基础上，现在侧重于由应力路径、几何、岩性和土工结构控制的演化损伤，以及4D隧道施工序列中EDZ/HDZ的时间依赖性和动态响应。最终结果将是脆性岩石深层施工行为预测和风险管理的重大改进，提高工人的安全性，支持可靠性和监测有效性。这项工作将大大提高初步工程评估和设计的可靠性，显著降低风险成本，提高价值数十亿美元的加拿大地下基础设施项目的可行性。***5名博士，7名硕士和3名USRA将在DG研究项目中接受培训，并获得重要的国内和国际曝光。* * * * * * * *

Disposal of high-level nuclear waste is a critical engineering challenge for all countries that generate nuclear power. The expert consensus is that underground disposal is the only viable long-term option. Canada, along with numerous countries, is moving forward with research and advanced plans for high-level (spent fuel) waste disposal and is currently in the site selection process for its own underground repository. The ultimate cost to Canadians, of such a repository, will be 10's of $Billions and the long-term viability and safety relies on management of the Excavation Damage Zone (EDZ) induced around repository infrastructure. Safety assessment is primarily concerned with maximum extent of EDZ and the gradient of increased fluid mobility within this damaged halo. ***Within the EDZ is the more fractured highly damaged zone (HDZ) near the excavation boundary. The staged, time-dependent and dynamic response of the EDZ/HDZ is also a critical issue in deep tunnelling with comparably high economic value at stake. In Canada and around the world, tunnels are being developed at increasing depths in brittle rockmasses for civil infrastructure or mine access. While generally considered in mining, brittle response of the HDZ due to construction has often been overlooked at the design stage in many recent world-class tunnelling projects, with serious impacts on worker safety, delays and increased costs.***In nuclear waste repositories, detectable HDZ in shafts is typically removed at the end of service life prior to backfilling and is therefore not considered in shaft safety assessment. The nature and time-dependent response of the HDZ during and after construction, will nevertheless impact the subsequent EDZ behaviour. It will also be an engineering challenge in terms of sequencing, safety and support. Different candidate sites will have different predicted levels of brittle HDZ, and degrees of dynamic rupture, which must be recognized prior to construction to enable adjustments in design.***Proposed research funded by this Discovery Grant builds on previous NSERC-funded progress (characterizing the general nature of damage initiation), focusing now on evolving damage controlled by stress path, geometry, lithology and geostructure, and on the time-dependent nature and dynamic response of EDZ/HDZ during the 4D tunnel construction sequence. The end result will be major improvements in behavioural prediction and risk management for deep construction in brittle rock, improving worker safety, support reliability and monitoring effectiveness. This work will create a step change in*reliability of preliminary engineering assessments and designs, significantly*reducing risk costs and improving project viability for Canadian underground infrastructure worth $Billions.***5 PhD's, 7MSc's and 3 USRA's will trained during this DG research program and gain significant national and international exposure. ********